Internal cam finishing apparatus



June 27, 1967 G. WINER 3,327,430

INTERNAL- (JAM FINISHING APPARATUS Filed Dec. 6, 1965 2 Sheets-Sheet 1 I z, I I

FIG.2

1N VEN TOR.

[R V/NG G. l V/NER A? TORNE Kr June 1957 I G. WINER 3,327,430

INTERNAL CAM FINISHING APPARATUS Filed Dec. 6, 1965 2 Sheets-Sheet 2 IN VEN TOR.

[R V/NG G. I/V/NER B Y A TTORNE Kr United States Patent Ofi ice 3,327,430 Patented June 27, 1967 3,327,431) INTERNAL 6AM FINISHING APPARATUS Irving G. Winer, 3241 Kentucky Ave. 5., St. Louis Park, Minn. 55426 Filed Dec. 6, 1965, Ser. No. 511,742 Claims. (Cl. 51-144) This application is a continuation-in-part of my copending application Ser. No. 325,284, filed Nov. 21, 1963, for Cam Finishing Apparatus, now Patent No. 3,222,- 822 issued Dec. 14, 1965.

This invention relates to apparatus for finishing internal cams and similar parts and Work pieces requiring smoothly finished internal edge surfaces. More particularly the invention is directed to apparatus for providing internal cams with a highly polished precision finish on their internal working edge faces.

The invention is illustrated in the accompanying drawings in which the same numerals are used to identify corresponding parts and in which:

FIGURE 1 is a top plan view of the internal cam finishing apparatus according to the present invention;

FIGURE 2 is a front elevation, partly in section, of the apparatus;

FIGURE 3 is an enlarged fragmentary section in elevation of the cam finishing portion of the apparatus;

FIGURE 4 is a fragmentary and enlarged tranverse section, on the line 44 of FIGURE 3 and in the direction of the arrows, showing the relation of a cam being finished with the finishing abrasive means; and

FIGURE 5 is a side elevation, partly in section, on the line 5-5 of FIGURE 1.

Referring now to the drawings, the apparatus comprises generally a pedestal frame or standard 11 adapted to be supported on any suitable base and which in turn supports a fiat horizontal top working platform 12. On one side of the apparatus there is mounted a motor 14 supported by an adjustable bracket 15 and having a driven shaft 16, to which is attached a drum 17. An endless belt 18 carrying a coating of fine abrasive material on its outer surface is driven by the motor through the shaft 16 and drum 17. Drum 17 may be flanged or unfianged and its belt engaging surfaces are desirably composed of or coated with rubber or other friction material.

On the top platform 12 of the apparatus spaced back from the front edge there is a bracket 19 which supports an elongated rocker arm 21 for pivotal movement on a shaft 20 carried in the bracket. At the opposite end of the rocker arm 21 from its axis of rotation about the pivot 20 there is journalled a spindle 22 for rotation relative to the rocker arm, and preferably for simultaneous reciprocating motion. Shaft 20 and spindle 22 are both preferably journalled in hardened steel bushings for minim-um wear and maximum life.

Spindle 22 is rotated by virtue of attachment to the drive shaft of a second motor 23 mounted on a plate 27. The .plate is provided with a slot 28 at one end which engages the shaft 20 so as to hold the motor 23 against rotation relative to the rocker arm, so as to impart rotary motion to the spindle.

As described hereinafter, it is desirable that the spindle 22 reciprocate relative to the rocker arm 21 so as to distribute wear uniformly across the abrasive belt 18. One means of accomplishing such reciprocation is provided by a face cam 24 fixed to the spindle 22 for rotation therewith. A rotary cam follower 25 mounted on a shaft supported by a post or bracket 26 mounted on the top of the rocker arm 21 bears against the working face of the cam 24. A plurality of coil springs 31 extending between the plate 27 mounting the motor 23 and posts 29 extending on opposite sides of the rocker arm resiliently and uniformly urge the cam follower 25 against the face of the cam 24 at all times. As the spindle 22 rotates the cam 24 causes the motor 23 and the plate 27 supporting the motor to be urged closer to and farther away from the rocker arm causing reciprocal movement of the spindle relative to the rocker arm.

The cam 32 to be finished is supported at the free end of the spindle 22 on the opposite side of the rocker arm 21 from the motor 23 and reciprocating cam 24. The cam 32 to be finished is secured to the spindle for rotation therewith along with a master cam 31 whose contours are desired to be exactly duplicated in the cam to be finished.

One means by which the master cam and cam to be finished may be mounted for rotation together is best shown in FIGURES 3 and 4. A face plate 33 is afiixed to the free end of spindle 22. Master cam 31 is desirably spaced from face plate 33 by means of a spacer ring 34. A further spacer ring 35 of brass or other non-magnetic material is fitted with a plurality of longitudinally extending magnets 36 whose ends are co-planar with the ends of the ring 35 and one end of ring 35 is butted against master cam 31. The cam 32 to be finished is then butted up against the opposite end of the spacer ring 35 and held there by the attractive force of the magnets. The cams and spacers are located and positioned relative to one another by means of a pair of timing pins 37 press fit into and extending from the spindle face plate 33 through the spacer ring 34, master cam 31 and spacer ring 35 and projecting from the end face of the spacer ring 35 to fit into locating holes provided in each of the cams to be finished for purposes of alignment. It will be readily seen that both cams will rotate and reciprocate with the spindle and with each other simultaneously.

A solid stable block 38 extends upwardly from the top of the platform. The inner face of block 38 extends transversely of the axis of spindle 22 and firmly and solidly supports a small diameter pin 39 which is preferably formed from heat resistant and rear resistant ceramic material, such as alumina, silicon carbide and the like, or tool steel, spaced above and in approximate vertical alignment with the axis of the spindle. The outermost extremity 40 of this pin 39 is of slightly greater, but

position to be in contact with the extension 40 of pin 39. The effect of this is that the master cam causes the,

rocker arm, along with the spindle and motor 23 and associated mechanism, to move on the rocker arm pivot up or down depending upon the particular interior contour of the master cam in contact with the follower pin at any instant.

The endless abrasive belt 18 passes at high speed over the inner portion of pin 39 between block 38 and extension 40 and the interior edges of the cam 32 to be finished move in contact with the abrasive belt as it passes around the pin and as the cam 32 rotates with the spindle. The portion of pin 39 between the face of block 38 and extension 40 is in precise axial alignment with the master cam follower pin extension 40 but is of lesser radius by an emount equal to the thickness of the abrasive belt, in order to insure that the cam to be finished will 1% inch diameter 7 to inch radius).

In order to permit annular cam 32 with its internal cam surfaces to fit over pin 39, while at the same time permitting abrasive belt 18 to engage the surface of the' pin and the internal cam surfaces, special guide means for the abrasive belt must be provided. These guide means comprise a pair of parallel spaced apart guide pins 41 and 42, each preferably made from heat resistant and wear resistant material such as are pin 39 and cam follower extension 40. Guide pins 41 and 42 are supported by block 38. They are disposed at approximately a 45 angle relative to'the inside face surface of block 38 and extend upwardly until their ends are spaced on opposite sides of and immediately below the end of pin 39 at approximately its juncture with cam follower extension 40.

Guide pins 41 and 42 are disposed generally parallel on opposite sides of a slot 43 in block '38 through which the abrasive belt 18 is threaded in its path from drum 17 to pin 39. It will be observed that the abrasive side of belt 18 engages the surface of drum 17. Slot 43 is narrow, vertical and substantially in alignment with the axis of spindle 22. -It is sufficiently wide to permit the sections of belt traveling through it in opposite directions to be spaced apart so as not to abrade one another.

The path of travel of the belt is from drum 17 through slot 43 in a generally horizontal path, and then around one of the angular guide pins disposed at a 45 angle to execute a right angle change in direction and to expose the abrasive coated surface for contact with the cam whose internal edges are to be finished. The belt then travels vertically upwardly around pin 39 and then immediately vertically downwardly to and around the other angular guide pin. The direction of travel of the belt is again given a 90 turn and the exposed side of the belt is again reversed and the belt travels through slot 43 on its return path to drum 17. As best seen in FIGURE 4, guide pins 41 and 42 are closely spaced from one another and from web support pin 39*, and the path of travel of the belt from one guide pin to the support pin is at an acute angle relative to the path of travel of the belt from the support pin to the other guide pin.

A pair of guide rollers 44 each supported in a bracket 45 on the outside face of block 38 on opposite sides of slot 43 are desirably provided to guide abrasive belt 18 so as not to travel in rubbing engagement with the side walls of slot 43. A bolt 46 extends through the top end of block 38 approximately perpendicular to slot 43 and pin 39 to permit removal of pin 39 for easy threading of belt 18 through slot 4'3 for replacement of the belt while at the same time insuring rigid mounting of pin 39.

The cam finishing operation is performed as a result of contact of the inside cam surface in engagement with the high speed moving abrasive belt 18 as it passes over the top edge of pin 39. Depending upon the amount of material to be finished from the cam 32 in the finishing operation, the cam 32 to be finished may initially function as the cam for controlling movement of the rocker arm and associated mechanism until the inside edge contours of that cam have been reduced sufficiently to bring the master cam 31 into contact with the cam follower pin extension 40.

The rocker arm is desirably formed of relatively lightweight material. The weight of the rocker arm and the mechanism associated with it largely determines the pressure under which the cam to be finished is brought into contact with the abrasive belt. Within reasonable limits, the longer the rocker arm the more precise results may be obtained. By means of the apparatus of the present invention internal cam edges may be consistently provided with finishes in the range from 2.1 to 2 micro-inch finish. The apparatus, according to the present invention, is not limited to the finishing of internal concave cam contours but may successfully and consistently finish cams whose internal surfaces have convex as well as concave contours.

It is apparent that many modifications and variations of this invention as hereinbefore set forth may be made without departing from the spirit and scope thereof. The

4. specific embodiments described are given by way of example only and the invention is limited only by the terms of the appended claims.

I claim:

1. Apparatus for finishing the internal surfaces of a generally annular workpiece, which apparatus comprises (A) static in support means for supporting a moving abrasive web in working contact with a workpiece,

(B) the web supporting surface of said support means having a radius of from to 1, inch and being adapted to fit inside of and be surrounded by a generally annular workpiece having internal surfaces to be finished,

(C) drive means for causing rapid movement of an elongated endless web of abrasive material over said web support means, and

(D) a pair of closely spacedapart guide means for said abrasive web for diverting the path of travel of said web over said Web support means interior of said generally annular workpiece the path of travel of said Web from one of said guide means to said support means being at an acute angle relative to the path of travel of said web from said support means to the other of said guide means.

2. Apparatus according to claim 1 further characterized in that said guide means for said abrasive web comprises (A) a pair of static guide pins angularly disposed relative to said web support means,

(B) said guide pins being parallel, and

(C) the ends of said guide pins being closely adjacent to said web support means.

3. Apparatus according to claim 2 further characterized in that said guide pins lie in a plane disposed at an angle of about 45 relative to the longitudinal axis of the web support means.

4. Apparatus according to claim 1 further characterized gether to urge the internal edge surface of said workpiece into resilient contact with an abrasive web moving over said web support means.

5. Apparatus according to claim 4 further characterized in that said apparatus includes a stationary portion and a relatively movable portion;

said stationary portion including said abrasive web support means,

said abrasive web drive means and said guide means for said abrasive web, and said relatively movable portion including said workpiece supporting means.

6. Apparatus for finely finishing the surfaces of in-. ternal edge cams to the contours of a master cam which apparatus comprises a stationary portion and a relatively movable portion;

said stationary portion including web support means in the form of a firmly and rigidly mounted static abrasive web support pin and an integral axially aligned master cam follower pin, guide means for an abrasive web for diverting the path of travel of said web over said web support means interior of said internal edge cam, drive means for causing rapid movement of said endless web of abrasive material over said guide means and said abrasive web support pin, and

mounting means for pivotally supporting one end of a rocker arm; said relatively movable portion comprising a rocker arm pivotally supported in said stationary mounting means for limited movement,

a spindle journalled for rotation in said arm on an axis spaced generally horizontally from and parallel to the pivotal axis, and parallel to and spaced from and underlying the axis of the stationary pins,

drive means for rotating said spindle relative to said arm, and

means adapted to secure a master cam and at least one generally annular cam to be finished to said spindle for rotation therewith, said securing means adapted to secure said master cam to said spindle with its internal edges surrounding and top portion of its internal edges overlying said cam follower pin and said cam to be finished with its internal edges surrounding and top portion of its internal edges overlying said abrasive web support pin;

said relatively movable portion adapted to rotate said cams in internal edge contact with said stationary pins under force of gravity imposed by said movable portion, whereby the contours of said master cam are precisely reproduced in said ca-rn to be finished.

7. Apparatus according to claim 6 further characterized in that said spindle is journalled for simultaneous reci rocal movement as it rotates.

8. Apparatus according to claim 6 further characterized in that the radius of said stationary cam follower pin is greater than the radius of the abrasive web supporting pin by the thickness of the abrasive web, whereby the master cam may have the same dimensions as the finished dimensions of the cam to be finished.

9. Apparatus according to claim 6 further characterized in that said drive means for said abrasive web comprises a motor having a drum of substantially greater diameter than the diameter of the abrasive web supporting pin secured to its driven shaft, the axis of said driven being perpendicular to the axis of said pin, said shaft being spaced laterally from said pin, said drum being disposed below said pin, a parallel pair of guide pins angularly disposed relative to said web supporting pin, the tips of said guide pins being adjacent to but spaced on opposite sides of said web supporting pin to change the direction of travel of the abrasive web from said drum up and around said web supporting pin.

10. Apparatus according to claim 6 further characterized in that said means for securing said master cam and cam to be finished to said spindle includes a face plate on one end of said spindle adapted to rigidly support said master cam, a non-magnetic spacer ring the radius of whose inner periphery is greater than the largest internal radius of the earns, a plurality of magnetic elements in the end surfaces of said spacer ring to hold said cams by magnetic attraction and locating means to position said cams and prevent relative movement thereof.

References Cited UNITED STATES PATENTS 2,751,724 6/1956 Polzer 51-141 ROBERT C. RIORDON, Primary Examiner. L. S. SELMAN, D. G. KELLY, Assistant Examiners. 

1. APPARATUS FOR FINISHING THE INTERNAL SURFACES OF A GENERALLY ANNULAR WORKPIECE, WHICH APPARATUS COMPRISES (A) STATIC PIN SUPPORT MEANS FOR SUPPORTING A MOVING ABRASIVE WEB IN WORKING CONTACT WITH A WORKPIECE, (B) THE WEB SUPPORTING SURFACE OF SAID SUPPORT MEANS HAVING A RADIUS OF FROM 3/32 TO 5/8 INCH AND BEING ADAPTED TO FIT INSIDE OF AND BE SURROUNDED BY A GENERALLY ANNULAR WORKPIECE HAVING INTERNAL SURFACES TO BE FINISHED, (C) DRIVE MEANS FOR CAUSING RAPID MOVEMENT OF AN ELONGATED ENDLESS WEB OF ABRASIVE MATERIAL OVER SAID WEB SUPPORT MEANS, AND (D) A PAIR OF CLOSELY SPACED APART GUIDE MEANS FOR SAID ABRASIVE WEB FOR DIVERTING THE PATH OF TRAVEL OF SAID WEB OVER SAID WEB SUPPORT MEANS INTERIOR OF SAID GENERALLY ANNULAR WORKPIECE THE PATH OF TRAVEL OF SAID WEB FROM ONE OF SAID GUIDE MEANS TO SAID SUPPORT MEANS BEING AT AN ACUTE ANGLE RELATIVE TO THE PATH OF TRAVEL OF SAID WEB FROM SAID SUPPORT MEANS TO THE OTHER OF SAID GUIDE MEANS. 